Stereophonic sound output apparatus and early reflection generation method thereof

A stereophonic sound output apparatus and an early reflection generation method thereof. The stereophonic sound output apparatus includes an early reflection generator to implement an early reflection when a 5.1 channel audio signal is down-mixed to a 2-channel audio signal to play back a 5.1 channel audio signal through a 2-channel headphone. The early reflection generator generates early reflections in pairs in which there is an appropriate time difference between the left side reflections and the right side reflections by generating an interaural time difference between two input audio signals and filtering. It is possible to copy the characteristics of early reflections in a real listening room. It is also possible to implement an early reflection similar to a real reflection measured in an apparatus for playing back the 5.1 channel audio signal through 2-channel headphone. A natural 5.1 channel effect may also be obtained using little computation.